PCI interrupt allocation question..

[Bernd Walter]

On Tue, Jan 13, 2004 at 04:14:10PM -0800, Julian Elischer wrote:
> 
> 
> On Wed, 14 Jan 2004, Stijn Hoop wrote:
> 
> > On Tue, Jan 13, 2004 at 03:26:00PM -0800, Julian Elischer wrote:
> > > The kernel includes teh ichsmb driver to try access the SMBus 
> > > for temperature reading reasons (yes I know I can do it other ways..)
> > > 
> > > Any thoughts that move me towards getting th eichsmb driver working on
> > > this machine are welcome.
> > 
> > Make sure that the mainboard really does support SMBus -- it turns out that
> > this is optional. The ICH docs talk about a bit that should be enabled in the
> > PCI config when SMB is present. I ran into this once, it should be documented
> > in the archives (of -current off the top of my head). OTOH, I didn't even
> > succeed in getting an ichsmb device probed so this might be something totally
> > unrelated.

SMBus is absolutely not optional because it's required for SPD eeproms.

> > FWIW, I had to try other ways to get the temperature (xmbmon & related). I
> > don't have the box anymore or I'd show you the exact config...
> 
> xmbmon uses the SMBus to read the temperatures but it does it from
> userland using direct read and write operations
> and when there are timing glitches caused by the process not getting
> scheduled quite quick enough you get garbage results..
> teh theory is that the kernel driver wouldn't be susceptible to this
> but it looks like unless I resort to polling I will not be able to use
> it because it relies on the interrupts and they are not being delivered.

ichsmb(4) does a different addressing on smbus as other smbus drivers.
I'm about to validate all SMBus drivers to harmonise this point.
Also software regulary forgets about different smb.h include path on 5.x

> ASUS motherboards actually turn off the SMBus. (why?)

A very good question - I'm in tight contact with Asus germany to get
that answered, but even they doesn't seem to get a satisfying answer
from taiwan.
It seems that they don't want customers to tamper with SMBus :(

> So you need to turn it back on before you can read the temperatures..

Use ACPI...
Well - it's evil after all, because I sell add on products for SMBus
for which ACPI is not an option.

-- 
B.Walter                   BWCT                http://www.bwct.de
ticso at bwct.de                                  info at bwct.de